1. Field of the Invention
The present invention relates to a transport system for the implementation of electrolytic deposition, coating or etching; and more particularly, relates to an apparatus for selective electrolytic metallization and deposition utilizing a fluid head arrangement. The invention is also directed to a method of making and maintaining an electrical contact with a product being processed in a transport system employed for selective electrolytic metallization and deposition, coating or etching. Furthermore, the invention is also directed to a method of making and maintaining an electrical contact with a product being processed as described herein, utilizing a fluid head arrangement.
A critical feature of any electrolytic process, particularly such as may be employed for the electrolytic metallization or deposition of metallic materials on a substrate is to be able to make good electrical contact with hardware on the substrate; for example, such as circuit boards, which are to be processed through the electrolytic metallization and deposition operation. In some instances, in order to implement the foregoing there is employed a type of well known apparatus employing a so-called fluid head design, incorporating electrodes which can be activated for implementing the metallization and deposition processes. Ordinarily, a fluid head does not readily enable the processing of discrete structures or product which are transported in separate parts or piecewise, but rather is adapted for processing continuous foils or webs forming the substrate, but which will still maintain electrical contact with each part. Processing with a fluid head is normally considered to be better suited to the implementing of reel to reel applications of the electrolytic metallization and deposition process, where a communing bar can be fabricated within the roll or web of material which is to be processed. However, without the capability of providing a continuous electrical contact, these processes are impossible to implement within the construction or format of a fluid head for individual printed circuit board processing.
Basically, conventional vertical or horizontal electrolytic metallization devices typically handle a standard, and very specific, size panel, in essence, a substrate, for their everyday production. When the size of the panel varies, especially in connection with processing with horizontal devices, ordinarily the device has to be shut down and the electrodes baffled so that the xe2x80x9cactivexe2x80x9d area is retained within the size of the panel which is to be transported. This activity requires that the device be shut down completely, opened up and modified which, in turn, has to be then implemented a second time in order to return to the original panel size. This results in a significant amount of non-productive downtime, as well as requiring engineering supervision. On panels with varying circuit densities, if processed by means of electro-pattern plating, there are also encountered problems with varying thickness in the deposition due to uniformity of the current density across the single large electrode which is typically employed in conventional platers.
Various structures are currently disclosed in the prior art or employed in carrying out metallizing process, such as the electrolytic deposition onto a substrate of metallic materials, for example, such as copper in order to produce electrolytic copper foils through the employment of a rotating cathode drum and an anode or plurality of sub-anodes which are located opposite the cathode drum.
Kubo, et al., U.S. Pat. No. 5,326,455 discloses a method and an apparatus for the production of electrolytic copper foil, wherein the apparatus utilizes a bath rather than one or more fluid heads for plating the foil, or alternatively employs a plurality of anodes with a single fluid head. The individual anodes can be controlled with respect to the quantity of electricity being supplied so as to provide for a uniform electrolytic deposition of a metallic material across the foil surface. Erickson et al., U.S. Pat. No. 5,389,214 discloses a fluid treatment system, wherein electrically reconfigurable electrode arrangements are employed, and in which a controller alters the effective separation area between the active electrode in response to resistivity variations so as to provide an optimal operation of the system. There is no workpiece provided for effectuating electrolytic deposition of metallic material, but rather the disclosure is directed to the treatment of fluids.
Blasing, et al., U.S. Pat. No. 5,292,424 pertains to a method for controlling a work cycle in electroplating plants, wherein different levels of electrical currents are applied to a series of adjacently located electrodes. This structure is similar in operation to Kubo, et al., U.S. Pat. No. 5,326,455 due to the utilization of baths in order to derive the electrolytic deposition of the metallic materials.
Komoto, et al., U.S. Pat. Nos. 4,749,460 and 4,765,878, each provide for an apparatus for electrolytic plating wherein the plating currents of a plurality of successive plating cells are automatically controlled in accordance with specific conditions in order to maintain uniform thickness of the metallic material which is being deposited onto a substrate.
Saprokhin, et al., U.S. Pat. No. 4,511,440 discloses a process for the electrolytic production of fluorine; however, in which there is no individual control of an electrical power supply to anodes. Furthermore, there is no disclosure of any workpiece which is coated through the deposition of a metallic material by means of electrolytic plating operation, and this publication is merely directed to the production of fluorine gas.
Schober, U.S. Pat. No. 4,164,454 discloses a continuous line for plating on intermittent lengths of metallic strip material, wherein workpieces are moved past a plating apparatus with no provision being made for any individual control of a supply of electrical current to the anodes.
In essence, none of the prior art publications as set forth hereinabove disclose a novel and inventive concept which is directed to incorporating the advantages of currently employed fluid head technology into the implementation an electrolytic metallization, coating or etching process, or electrolytic plating, which would ordinarily not be considered to be possible to effectuate. Basically, the invention is directed to the provision of an external transport system wherein a cathode drum brush for supplying electrical current and a drive wheel of a substrate transport system are in intimate contact with comments or hardware which is to be processed, such as printed circuit boards or the like, thereby facilitating continuous electrical contact with the components being processed which conveyed through the transport system, or fluid head during any specific period of time.
Pursuant to the invention there is disclosed an electrically conductive brush and drive wheel on opposite side edges of the workpiece being processed, which in essence contacts the workpiece enabling individual sheets or continuous rolls or webs to be processed during conveyance through transport system, the latter of which may comprise a fluid head, and by using the cathode brush and drive wheel for workpiece conveyance and for supplying electrical current.
In connection with the foregoing, the invention is directed to the provision of an electrolytic plating apparatus which includes a fluid-containing head having a fluid input; an arrangement to move workpieces past the fluid head, with a plurality of anodes being located within the head, each anode being individually controllable in its electrical potential in order to provide a specific electrical field strength at different positions of the workpiece, while the workpiece is moving past the fluid head. In particular, the brush cathode and the drive wheel which are located externally of the transport system, such as the fluid head, are at all times physical and electrical contact with the workpiece during the electrolytic plating procedure, so as to maintain a constant electrical potential therewith.
By utilizing the concepts of the present invention, it is consequently possible to produce an electrolytic metallization and deposition system that can alleviate essentially all of the problems normally associated with conventional systems, which are incurred when attempting to manufacture printed circuit boards of various dimensions, as well as differences in circuit densities on the same process line.
Pursuant to the inventive structure, banks of anodes (or cathodes) are situated within the fluid head body such that at any given time either all or only specific areas within the working dimensions of the device can be activated from a keyboard control station. This allows for continuous operation of the system with only momentary interruptions for resetting the xe2x80x9cactivexe2x80x9d area within the system. Compensation for extremely dense as well as very sparse areas of circuitry on the same panel or circuit board can be adjusted for, a feature not attainable on conventional systems. Thus, by employing the inventive concept, panel size and variations of circuit density no longer present any problem.
This concept system can be utilized for any type of electrochemical deposition process. Examples would be for CU, NI and AU, as well as any other metals. It can also be used to enhance coating operations, such as electrophoretic deposition processes. Another use would be to enhance electrochemical etching techniques, essentially anything that would require a potential in order to be deposited or etched away from a substrate.
Accordingly, it is an object of the present invention to provide an apparatus comprising a transport system for conveying a workpiece for the purpose of implementing electrolytic metallization or deposition, including a plurality of anodes each individually controllable to an electrical potential, and with a brush cathode and drive wheel arrangement being in contact with the workpiece at all times during electrolytic plating.
A further object of the invention resides in the provision of a transport system as described herein which comprises a fluid head having a fluid input, with the transport system being able to move the workpiece past the fluid head, and wherein the brush cathode and the drive wheel structure for conveying the work piece are located externally of the fluid head and are in constant contact with the workpiece so as to be able to apply a constant electrical potential thereto.
Another object of the present invention resides in the provision of a method for making and maintaining electrical contact with a product being processed in a transport system utilizing a cathode brush and drive wheel for conveyance and concurrent electrical conduction, and with a plurality of anodes being selectively activatable in order to maintain predetermined electroplating conditions on a substrate.